Line marker buoy



FIG. 1 is a front elevational view of a line marker buoy showing my new design, the rear being a mirror image;

FIG. 2 is a side elevational view thereof, the opposite side being a mirror image;

FIG. 3 is a bottom plan view thereof on a reduced scale; and

FIG. 4 is a top plan view thereof on a reduced scale. 

The ornamental design for a line marker buoy, as shown and described. 